close

Вход

Забыли?

вход по аккаунту

JP2017126946

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2017126946
Abstract: To provide an acoustic diaphragm excellent in Young's modulus and internal loss (tan
δ). SOLUTION: The acoustic diaphragm of the present invention is composed of a paper sheet
substantially including only cellulose nanofibers. In one embodiment, the cellulose nanofibers are
unoxidized cellulose nanofibers. [Selected figure] Figure 1
Acoustic diaphragm
[0001]
The present invention relates to an acoustic diaphragm. More particularly, the present invention
relates to an acoustic diaphragm used for speakers, headphones, and the like.
[0002]
Generally, the characteristics required for an acoustic diaphragm used for speakers, headphones,
etc. include various strengths, high airtightness, high Young's modulus (elastic modulus, rigidity),
and internal loss (tan δ) Is large). In order to meet such requirements, materials and structures
of acoustic diaphragms are continuously studied.
[0003]
JP, 2013-42405, A JP, 2011-130401, A
10-05-2019
1
[0004]
The present invention has been made to solve the above-described conventional problems, and
an object thereof is to provide an acoustic diaphragm excellent in Young's modulus and internal
loss (tan δ).
[0005]
The acoustic diaphragm of the present invention is composed of a paper sheet substantially
containing only cellulose nanofibers.
In one embodiment, the cellulose nanofibers are unoxidized cellulose nanofibers.
[0006]
The acoustic diaphragm of the present invention is excellent in Young's modulus and internal
loss (tan δ) by being composed of cellulose nanofibers.
[0007]
It is a figure which shows the frequency characteristic of the acoustic diaphragm obtained by
Example 2, the comparative example 2, and the comparative example 3. FIG.
[0008]
The acoustic diaphragm according to the embodiment of the present invention is obtained by
papermaking of cellulose nanofibers.
The acoustic diaphragm is composed of a papermaking body substantially containing only
cellulose nanofibers.
By using a paper body of cellulose nanofibers, an acoustic diaphragm having a fine structure in
which the fibers are strongly bonded by hydrogen bonds can be obtained. As a result, an acoustic
10-05-2019
2
diaphragm having an excellent Young's modulus can be obtained.
Further, the acoustic diaphragm of the present invention is excellent in density, airtightness,
strength, etc., and can have a wide high-frequency reproduction band and can realize excellent
sound quality.
[0009]
Cellulose nanofibers refer to cellulose fibers having a nanosized fiber diameter. The fiber
diameter (number average diameter) of the cellulose nanofibers is, for example, 3 nm to 100 nm.
The length (number average length) of the cellulose nanofibers is, for example, 0.1 μm to 100
μm. The aspect ratio (length / diameter) of cellulose nanofibers is, for example, 50 to 1000. The
fiber diameter of pulp is usually 1 μm or more, and in the present specification, cellulose
nanofibers and pulp are distinguished by the fiber diameter.
[0010]
The acoustic diaphragm according to the embodiment of the present invention is different from
the conventional acoustic diaphragm in which a small amount of cellulose nanofibers of 1/1000
or less is added and mixed with pulp fibers having a large fiber diameter. The papermaking body
containing only cellulose nanofibers becomes denser, strong hydrogen bonds can be generated,
and the air density also becomes much larger. Therefore, as an acoustic diaphragm, it is excellent
in the ability to push out the air which is a medium of a sound wave, and can realize the
outstanding sound quality.
[0011]
As a method of producing cellulose nanofibers, for example, a water-on-collision method (ACC
method) in which suspensions obtained by dispersing pulp in water are made to collide with each
other to break down and make them finer; Methods are included. As the mechanical treatment,
for example, treatment to refine the cellulose raw material using a low pressure homogenizer,
high pressure homogenizer, grinder, cutter mill, jet mill, short screw extruder, twin screw
extruder, ultrasonic stirrer etc. is mentioned. Be Cellulose nanofibers can also be produced by
defibrillation of cellulose raw materials by chemical treatment such as oxygen treatment or acid
10-05-2019
3
treatment, but in the present invention, there are counter-impact collision methods in water (ACC
method), machinery It is preferable to use unoxidized cellulose nanofibers obtained by chemical
treatment and the like. If unoxidized cellulose nanofibers are used, a paper sheet containing only
cellulose nanofibers can be formed, and an acoustic diaphragm excellent in the balance of
Young's modulus, internal loss (tan δ), airtightness and various strengths can be obtained.
[0012]
The cellulose raw material is not particularly limited, and any appropriate cellulose raw material
is used. Examples of cellulose raw materials include hardwood kraft pulp (LKP) such as hardwood
bleached kraft pulp (LBKP), hardwood non-bleached kraft pulp (LUKP), softwood bleached kraft
pulp (NBKP), softwood non-bleached kraft pulp (NUKP) Wood-derived kraft pulp; waste paper
pulp such as sulfite pulp and deinked pulp (DIP); grand pulp (GP), pressure-type ground pulp
(PGW), refiner ground pulp (RMP), thermo-mechanical pulp (TMP), chemi Mechanical pulp, such
as thermo mechanical pulp (CTMP), chemi mechanical pulp (CMP), chemi grand pulp (CGP), etc.
are mentioned. Alternatively, powdered cellulose obtained by pulverizing these pulps, or
microcrystalline cellulose obtained by purifying pulp by chemical treatment such as acid
hydrolysis may be used. Furthermore, non-wood pulp derived from kenaf, hemp, rice, bagasse,
bamboo, bamboo, cotton or the like may be used. In one embodiment, softwood-derived cellulose
is used as a raw material for cellulose nanofibers. By using cellulose derived from softwood, an
acoustic diaphragm having a higher Young's modulus can be obtained.
[0013]
In the present specification, containing substantially only cellulose nanofibers means that
the content ratio of cellulose nanofibers is 90 parts by weight or more with respect to 100 parts
by weight of the acoustic diaphragm. The content ratio of cellulose nanofibers is preferably 95
parts by weight or more, more preferably 98 parts by weight or more, and still more preferably
100 parts by weight with respect to 100 parts by weight of the acoustic diaphragm.
[0014]
The acoustic diaphragm may contain a very small amount of other components in addition to the
cellulose nanofibers. For example, wood pulp can be added at a content ratio of less than 10
parts by weight (preferably less than 5 parts by weight, more preferably less than 2 parts by
10-05-2019
4
weight) with respect to 100 parts by weight of the acoustic diaphragm. An acoustic diaphragm
containing cellulose nanofibers and a very small amount of wood pulp can be obtained by mixing
these materials. The above-mentioned wood pulp is not particularly limited, and wood pulp
usually used for an acoustic diaphragm may be adopted. For example, softwood pulp, hardwood
pulp and the like are used.
[0015]
The acoustic diaphragm may further contain other fibers as needed. Other fibers may be
appropriately selected depending on the purpose. For example, high-strength fibers may be
mixed if the purpose is to improve mechanical strength. Furthermore, fibers according to the
purpose (for example, deodorizing fibers, negative ion releasing fibers) may be mixed.
[0016]
The density of the acoustic diaphragm is preferably 0.45 g / cc or more, more preferably 0.5 g /
cc or more. If it is such a range, the acoustic diaphragm which is especially excellent in Young's
modulus can be obtained.
[0017]
The folding resistance of the acoustic diaphragm is preferably 1000 or more, more preferably
2000 or more, and still more preferably 2500 or more. The folding resistance is measured in
accordance with JIS P 8115.
[0018]
The rigidity of the acoustic diaphragm is preferably 1000 mgf to 5000 mgf, more preferably
1500 mgf to 3000 mgf. If it is such a range, the acoustic diaphragm which is especially excellent
in Young's modulus can be obtained. The stiffness is measured in accordance with JIS P 8125.
[0019]
10-05-2019
5
The tearing degree of the acoustic diaphragm is preferably 200 gf or more, more preferably 300
gf or more. The tearing degree is measured in accordance with JIS P 8116.
[0020]
The airtightness of the acoustic diaphragm is preferably 15 s / 100 cc or more, more preferably
100 s / 100 cc or more, and still more preferably 1000 s / 100 cc or more. The method of
measuring the tightness will be described later.
[0021]
The acoustic diaphragm of the present invention can be obtained by papermaking cellulose
nanofibers by any appropriate method, and thereafter forming a flat plate obtained by
papermaking into a predetermined shape. Preferably, non-woven fabric is used as papermaking
in papermaking. When non-woven fabric is used as a papermaking when making cellulose
nanofibers with a thin fiber diameter, the paper making process can be performed well.
[0022]
As a material which constitutes the above-mentioned non-woven fabric, for example, polyester
fiber, polyamide fiber, polyaramid fiber, polyolefin fiber, vinylon fiber, cellulose fiber,
regenerated cellulose fiber, and a plurality of copolymers thereof are mentioned. Fiber etc. are
mentioned.
[0023]
The basis weight of the non-woven fabric is preferably 50 g / m <2> to 200 g / m <2>, and more
preferably 100 g / m <2> to 150 g / m <2>.
If it is such a range, a papermaking process can be performed favorably.
10-05-2019
6
[0024]
The thickness of the non-woven fabric is preferably 0.2 mm to 1 mm, more preferably 0.3 mm to
0.7 mm. If it is such a range, a papermaking process can be performed favorably.
[0025]
Any appropriate method may be employed as a method of forming a flat plate obtained by
papermaking. As a specific example of the molding method, for example, heat press molding can
be mentioned. Alternatively, the acoustic diaphragm may be formed into a predetermined shape
suitable for a diaphragm such as a substantially cone shape, and then this may be hot-pressed.
Alternatively, the acoustic diaphragm may be formed into a predetermined shape suitable for a
diaphragm such as a substantially cone shape, and then formed and dried in an oven.
[0026]
The acoustic diaphragm of the present invention may have any suitable shape depending on the
purpose. For example, the acoustic diaphragm of the present invention may have a cone shape, a
dome shape, or any other shape.
[0027]
The acoustic diaphragm of the present invention can be applied to speakers or headphones for
any application. For example, the speaker using the diaphragm of the present invention may be
for on-vehicle use, for portable electronic devices (for example, a mobile phone, a portable music
player), or may be stationary. For example, the speaker using the diaphragm of the present
invention may have a large diameter, a medium diameter, or a small diameter. Preferably, it is
used for a small diameter speaker.
[0028]
Hereinafter, the present invention will be more specifically described by way of examples, but the
10-05-2019
7
present invention is not limited by these examples. The evaluation methods in the examples are
as follows. In the Examples and Comparative Examples, parts and percentages are by weight
unless otherwise indicated.
[0029]
<Evaluation> 1. Measurement of Young's modulus and internal loss (tan δ) Young's modulus and
internal loss (tan δ) of the obtained flat plate were measured by the vibration lead method
(cantilever, resonance method). Specifically, test pieces of 40 mm × 15 mm size are cut out from
the flat plates obtained in Examples and Comparative Examples, and Young's modulus and
internal loss (tan δ) at 23 ° C. are measured for each test piece. did. In the table, the average
value of 5 test pieces is shown.
[0030]
2. Test pieces of 40 mm × 15 mm in size were cut out of 5 pieces from the flat plate obtained in
the density example and the comparative example. Using a dial thickness gauge, the thickness
and weight of 4 points (ie, 4 points × 5 pieces in total 20 points) were measured for each piece,
and the average value of the density was determined from the values.
[0031]
3. Five test pieces of 50 mm × 50 mm in size were cut out from the flat plates obtained in the
airtightness examples and the comparative examples, respectively, and measured in accordance
with JIS P 8117. The average value is shown in the table.
[0032]
Example 1 In a paper making tank using non-woven fabric (polyester microfiber (3 μm) +
polyurethane resin 5%, fabric weight: 140 ± 10 g / m <2>, thickness: 0.55 ± 0.06 mm) as a wire
mesh A 0.1% by weight suspension of softwood-derived cellulose nanofibers (manufactured by
Chuetsu Pulp Industries Co., Ltd., fiber diameter: about 20 nm) is injected, paper making, and
then heat pressing using a molding die, micronano A flat plate consisting only of fibers (basis
10-05-2019
8
weight: 43.7 g / m <2>) was obtained. The obtained flat plate was subjected to the above
evaluations 1 to 3. The results are shown in Table 1.
[0033]
[Example 2] Paper was made under the same conditions and conditions as in Example 1, and
then heat pressed using a molding die to obtain a diaphragm for a headphone driver consisting
only of micro nanofibers. The frequency characteristics of the diaphragm were measured to
evaluate the sound quality. The results are shown in FIG.
[0034]
Comparative Example 1 BKP (beating degree: 500 cc) was paper-made and press-dried to obtain
a flat plate consisting only of BKP (basis weight: 48.5 g / m <2>). The obtained flat plate was
subjected to the above evaluations 1 to 3. The results are shown in Table 1.
[0035]
[Comparative Example 2] Paper was made under the same conditions and conditions as
Comparative Example 1 and then heat pressed using a molding die to obtain a headphone driver
diaphragm made of only BKP. The frequency characteristics of the diaphragm were measured to
evaluate the sound quality. The results are shown in FIG.
[0036]
Comparative Example 3 20 parts of softwood-derived cellulose nanofibers (manufactured by
Chuetsu Pulp Industries Co., Ltd., fiber diameter: about 20 nm) are blended with 100 parts of
BKP (beating degree of 500 cc) and mixed, and then using a molding die It was heat-pressed to
obtain a diaphragm for a headphone driver. The frequency characteristics of the diaphragm were
measured to evaluate the sound quality. The results are shown in FIG.
[0037]
10-05-2019
9
[0038]
As apparent from Table 1, the diaphragm made of only cellulose nanofibers has strong bonds
between fibers, and is excellent in physical properties such as density, Young's modulus and
airtightness.
In addition, as is apparent from FIG. 1, such a diaphragm increases the sound pressure in the
high region, and exhibits good characteristics and sound quality. In terms of sound quality, the
sound pressure in the high-frequency reproduction band has increased, the amount of
information has increased, the energy of the mid-high range has become easier to be radiated,
the S / N is better, and the gap in the mid-high range is better. In addition, the strength of the low
region was improved by improving the overall strength and air tightness.
[0039]
The acoustic diaphragm of the present invention can be suitably used as a speaker or headphone
for any application.
10-05-2019
10
1/--страниц
Пожаловаться на содержимое документа